There is widespread use of ball and socket type hitches for the towing of various types of vehicles. Most commonly a portion of the trailer hitch is permantly mounted upon the rear of the towing vehicle. This portion of the hitch includes a support plate securely mounted upon the vehicle and a ball member secured to that plate. This ball member typically has a spherical upper portion and a lower skirt portion, with the skirt portion having a flat surface to bear against the upper surface of the support plate. A bolt is utilized to secure the ball member to the support plate. This bolt may be an integral stud extending below the skirt portion to pass through a hole in the support plate and receive a locking nut and washer against the lower surface of the support plate. In alternative constructions, the bolt member may have a head below the support plate and extend upwardly into the skirt and spherical portion of the ball member. Other ball members in use have various other constructions with regard to the securing of the ball member to the support plate of the towing vehicle.
The towed member, frequently in the form of a trailer, has a tongue unit for extending toward the towing vehicle. This tongue terminates in a socket member to closely receive the ball member of the hitch. This socket member has a movable wedge or finger located therein which can be releasably secured against the undersurface of the spherical portion of the ball member such that the socket member is releasably secured to the ball member. For additional safety purposes, safety chains are releasably connected between the towing vehicle and the towed vehicle to prevent complete separation of the two vehicles if the connection between the ball and socket should, for any reason, become separated.
A problem that is frequently encountered is the unauthorized connection of the socket portion of the hitch unit to a towing vehicle not owned by the owner of the towed vehicle. For example, trailers used for camping, the transport of pleasure boats, etc., frequently are stored in garages or yards for extended periods of time. The theft of such trailers is a common occurrence if the trailer is left unattended. In addition, it is common practice for fishermen and the like to leave trailers coupled to their towing vehicle at or near launching ramps. Again, thievery of the trailer unit frequently occurs through the unauthorized connection of the socket member of the trailer to a ball member on another vehicle.
Several devices have been developed to at least minimize the unauthorized use of trailers and the like. One such device is shown in U.S. Pat. No. 3.226,133 issued to S. Geresy on Dec. 28, 1965. In this device, a separate "artificial" ball is provided which can be locked within the socket of a trailer hitch to prevent the insertion of another ball therein. This ball is held in place by several embodiments of appropriate mechanisms. Another type of "artificial" ball developed by the same inventor is shown in U.S. Pat. No. 3,237,969 issued on Mar. 1, 1966. Both of these devices prevent coupling to another ball as stated. However, with little effort, the trailer can be fastened to a towing vehicle by other means such that the trailer and contents may be stolen. In addition, neither of these devices provide for additional safety with regard to the connection of the ball and the socket for normal trailing.
One hitch structure that has been designed for increased safety is that shown in the patent to M. L. McCorkle, U.S. Pat. No. 3,442,534 issued on May 6, 1969. In this device, a safety bolt is inserted through the dome of the socket portion of the hitch to be threadably engaged in a hole in the top of the ball. This bolt carries a cap means of some type which prevents the complete separation of the socket from the ball.
Still another type of trailer hitch designed to achieve increased safety is that shown in U.S. Pat. No. 4,428,596 issued to T. G. Bell, et al., on Jan. 31, 1984. This device has an additional plate member carried by the ball portion of the hitch which can be lockably secured to the socket portion of the hitch away from the ball. There is no provision in this structure to prevent unauthorized use of the trailer.
Accordingly, it is a principal object of the present invention to provide a trailer hitch which can be used in a conventional manner and which provides for the prevention of unauthorized use of either the towing vehicle or the towed vehicle.
It is another object of the present invention to provide a trailer hitch which adds additional safety features to the connection between the towing vehicle and the towed vehicle.
These and other objects of the present invention will become apparant upon consideration of the drawings identified below and the following descriptive material.